Strip handling



June 28, 1966 F. L. VATH ETAL 3,253,261

STRIP HANDLING Filed April 13, 1964 5 Sheets-Sheet l June 28, 1966 VATH ETAL 3,258,261

STRIP HANDLING Filed April 13, 1964 5 Sheets-Sheet 2 FIG-3 14 A IC Company FIG-4 /4 ABC Company "w l I 20 32?] "I l I N VEN TORS FRANCIS LEO VATH RAYMOND CORNETT JESSE B. YOUNG WMM ATTORNEY June 28, 1966 F. L. VATH ETAL 3,258,261

STRIP HANDLING Filed April 13, 1964 5 Sheets-Sheet 5 o oTv o oooo on oooooooon/wooo i e 4 w a, 0 0 2 2 4 m 2 :22 7 2 8 I 6 6\\ 4 000 Jo 0000 4 Wllllflllnlflll m 0 000 00 0 00 A 8 a w n o m 2 9 W2 w C \f a A3 i 5 i m 6 1 7 li oooooor .w oooooooooo G I m M F H INVENTORS LEO VATH ATTORNEY United States Patent 015 3,258,261 Patented June 28, 1966 [ice 3,258,261 STRIP HANDLING Francis Leo Vath, Raymond Cornett, and Jesse B. Young,

Dayton, Ohio, assignors to The Standard Register Company, Dayton, Ohio, a corporation of Ohio Filed Apr. 13, 1964, Ser. No. 359,125 8 Claims. (Cl. 270-21) This invention relates to strip handling.

The invention relates more particularly to apparatus and a method of handling strip material in the preparation of business forms and the like.

This invention pertains to production of business forms which are provided with printed information and which are also provided with coded information in the form of holes punched through the form in predetermined positions thereof. This invention relates still more particularly to business forms produced from a continuous strip of stock material.

However, apparatus produced according to this invention and the method of this invention may be employed in the processing of strip material of various kinds, other than material for producing business forms.

In the past it has been customary to produce business forms from continuous strip material by using a machine which receives a continuous strip of stock material, prints on the material at predetermined locations, perforates the material at predetermined locations to provide business forms in the strip of stock material which is carried thereby. Then, such a machine folds the strip of stock material which carries the forms therein which are partially cut therefrom. Then it has been customary to take the folded stock material to a second machine which unfolds the strip, and applies numbering or other information to the forms formed in the strip. Such numbering or other information is applied by punching holes through the forms at certain predetermin d positions and also by applying such information in the form of printed numbers or letters or other indicia. Some of the information applied to the forms may be applied by conventional ink or by magnetic ink or the like.

It has been found that a machine which performs such functions as partially cutting and folding, as well as printing, must, by necessity, operate more slowly than if the machine should do only printing. Also, if a machine is to perform printing, partial cutting, and folding, the amount of set-up time upon the machine is considerably greater than if the machine is to perform printing only. Furthermore, in a printing press type of machine which also performs perforation operations, replacement or proper adjustment of perforating blades is time consuming. Also, in the use of a printing press type of machine for perforation of the stock material as well as printing thereupon, the perforating is done by a blade or blades against a hard cylinder. This results in a crushing effect and causes curved edges of the forms produced. Of course, forms having curved edges are objectionable in that they present numerous problems in machine feeding thereof.

Also, when perforating of stock material is carried out in the same machine which performs printing thereupon, the paper dust produced in the perforating operation may cause trouble in the printing operation. Also, in the assembly of a machine which is to perform both printing and perforating operations, the necessary tolerances among the parts of the machine, such as gearing and the like, must be very small and are diflicult and costly to obtain and maintain.

An object of this invention is to provide apparatus and a method for high speed production of business forms in a continuous strip of stock material.

Another object of this invention is to provide apparatus which performs unwinding of a rolled strip of stock material, applies information to the material in the form of properly positioned holes, prints information such as numbers or other indicia upon the material either by use of conventional types of inks and/or magnetic types of inks, perforates the material to create forms or the like in the material, the forms being partially severed from the stock material by the perforating operation.

Another object of this invention is to provide such apparatus which operates at a much higher rate of speed than any known apparatus which performs the same functions or operations.

Another object of this invention is to provide continuous strip handling apparatus having a plurality of units arranged in seriatim relationship in which some of the units operate upon the strip when the strip is stopped and in which some of the units operate upon the strip when the strip is in motion and in which all of the units operate together and perform sequential operations upon the strip.

Another object of this invention is to provide apparatus which produces partially severed forms in a continuous strip by use of a plurality of units operated in sequence in the production of each form.

Other objects and advantages reside in the construction of parts, the combination thereof, the method of manufacture, and the mode of operation, as will become more apparent from the following description.

In the drawings:

FIGURE 1 is a diagrammatic view of apparatus of this invention.

'FIGURE 2 is another diagrammatic view of apparatus of this invention, illustrating .the control means thereof.

FIGURE 3 is a fragmentary plan view illustrating an example of strip material as it enters the first and second units of the apparatus of this invention.

FIGURE 4 is a fragmentary plan view showing the strip material of FIGURE 3 as it enters the third unit of the apparatus of this invention.

FIGURE 5 is a fragmentary plan view showing the strip material of FIGUR'ES 3 and 4 as it enters the fourth unit of the apparatus of this invention.

FIGURE 6 is a fragmentary plan view showing the strip material of FIGURES 3, 4, and 5 as it enters the fifth unit of the apparatus of this invention.

FIGURE 7 is a fragmentary plan view showing another example of strip material as its enters the first and second units of the apparatus of this invention.

Referring to the drawings in detail, apparatus of this invention comprises a plurality of units shown in FIG- URES l and 2, which sequentially perform operations upon a strip or web of material 14 as the strip 14 moves from a roll 16 thereof. I

The strip material 14 may be card stock material or any other material used in producing business forms. Prior to being wound into the roll 16, the strip material 14 is provided with pin feed holes 18, which may appear, for example, in the manner shown in FiIG'U R-E 3. FIGURE 3 shows pin feed holes 18 in the two opposite edges of the strip 14.

Also, prior to being wound into the roll 16, the strip 14 may be printed thereupon. For example, if checks or the like are to be formed from the strip 14, a decorative border or outline or frame 19 of a blank check may be printed on the strip 14 along with any other information or wording 20, as illustrated in FIGURE 3, in the left hand portion thereof. Also, as shown in FIGURE 3, the right hand portion of the strip 14 may have a stub blank 22 printed thereon to receive information pertaining to a check prepared within the border 19 adjacent thereto.

Thus, FIGURE 3 shows an example of the appearance of the strip 14 of material as it moves from the roll 16 thereof.

Thus, the strip 14 moves from the roll 16 thereof and into an unwind unit 26. The unwind unit 26 draws the strip 14 from the roll 16 thereof and operates upon the strip 14 in a manner to remove the tendency of the strip 14 to curl. The unwind unit 26 continuously moves the strip 14 therethrough during operation of the apparatus.

The strip 14 passes from the unwind unit 26 and forms a loop 28. Then the strip 14 passes into a punch unit 30. The punch unit 30 has a punching portion 30a, shown in FIGURE 2, within which holes or apertures 32 are formed in the strip '14 within the outline 19, as shown in FIGURE 4. These holes 32 are so positioned and arranged that they provide certain information. For example, the punched holes 32 may provide a number for a check or provide other information.

The punch unit 30 also includes a verification portion 30b, shown in FIGURE 2. The verification portion 30b reads the information provided by the punched holes 32 and determines whether the information has been correctly applied by the punching portion 30a. The verification portion 3012 may consist of any suitable reader or checking device.

The punch unit 30 draws a given length of the strip 14 thereinto. Then that portion of the strip 14 within the punch unit 30 is stopped. Then as that portion of the strip 14 is stopped, a linearly movable head element 33, shown diagrammatically in FIGURE 1, moves downwardly toward the strip 14 and a punching element (not shown) carried by the head 33 punches holes 32 in the portion of the strip 14 which is within the punch portion 30a.

At the same instant of time that a punching operation occurs upon a portion of the strip 14 within the punching portion 30a of the punch unit 30, the verification portion 3011 reads the holes 32 which are in a portion of the strip 14 which is within the verification portion 30b. Of course, the holes 32 within the verification portion 30b at any given time are holes 32 which were punched into the strip 14 by the punch portion 30a immediately prior to movement of that portion of the strip 14 into the verification portion 30b.

Thus, the strip 14 moves through the punch unit 30 in a series of short movements which are separated by short intervals during which the strip 14 is at rest.

Then, the strip 14 passes from the punch unit 30 and forms a loop 34 between the punch unit 30 and a printer unit 36. The strip 14 then passes into the printer unit 36. Within the printer unit 36, numbering or other information referred to by reference numeral 38 shown in FIGURE is applied by a printing operation within each check blank outline 19. The printed information 38 ordinarily may confirm or agree with the information applied to the strip 14 in the form of the punched holes 32. The printer unit 36 may apply printed information to the strip 14 by use of magnetic inks or the like, and/ or by conventional inks. 7

It is to be understood that all of the printing upon the strip 14 may occur within the printer unit 36. In such event, there is no printing upon the strip 14 when it enters the apparatus of this invention.

The strip 14 moves continuously through the printer unit 36 and printing upon the strip 14 occurs while the strip 14 is in motion.

The strip 14 then passes from the printer unit 36 and forms a loop 40 between the printer unit 36 and a perforation unit 44. The perforation unit 44 may be of any suitable mechanism and may be mechanism made according to the invention disclosed in application Serial No. 340,176, filed January 27, 1964, and owned by the ass-ignees of this application.

The strip 14 moves through the perforation unit 44 in a series of short movements separated by very short intervals of no movement of the Web 14. During the periods in which the web 14 is stopped within the perforation unit 44, the web 14 is operated upon by a linearly reciprocally movable head 45, shown in FIGURE 1. The head 45 carries perforation elements (not shown) which perforate the strip 14 both transversely and longitudinally, as illustrated by perforations 46 in FIGURE 6. It is to be understood that the perforations 46 may be of any suitable shape or form. Thus, perforations 46 encompass both the check blank outline 19 and the stub 22 so that both the check blank within the outline 19 and the stub 22 are readily severable from the strip 14 but are carried by the strip 14.

Then the strip 14 passes from the perforation unit 44 and forms a loop 49 between the perforation unit 44 and a folder unit 50. The strip 14 moves continuously through the folder unit 50 without stopping during operation of the strip handling apparatus of this invention. The folder unit 50 may be any suitable type of folder device and may comprise the folder apparatus disclosed in application Serial No. 323,962, filed November 15, 1963, and owned by the a-ssignee of this application. The continuous strip 14 issues from the folder unit 50 in a folded condition, as illustrated diagrammatically in FIGURES l and 2. 7

As stated above, the unwind unit 26, the printer unit 36, and the folder unit 50 move the strip 14 continuously and without stopping the strip 14 during operation of the apparatus. However, the strip 14 moves through the punch unit 30 and through the perforation unit 44 in a series of short movements which are separated by short periods of no movement of the strip 14. The strip 14 is thus operated upon in the punch unit 30 and in the perforation unit 44 when there is no movement of the strip 14 and the strip 14 is operated upon in the other units while the strip 14 is in movement.

Thus, it is understood that strip handling apparatus of this invention includes a series of units which operate together upon the continuous strip 14 as the strip 14 moves from each unit to the next succeeding unit.

Motor means As illustrated in FIGURE 2, a main drive motor 60 has attached thereto any suitable speed control clutch 62, which may, for example, be an eddy current clutch or the like. An electric motor and eddy current speed control clutch produced as a unit by Eaton Mfg. Company as Model ACM has been found to serve very satisfactorily as the motor 60 and speed control clutch 62. Connected to the speed control clutch 62 is any suitable start-stop clutch 64, which may, for example, be a fluid operated clutch or the like. An electrically operated friction clutch brake sold by Eaton Mfg. Company and referred to as Dynator has been found to serve satisfactorily as the start-stop clutch 64.

Connected to the start-stop clutch 64 is a line shaft 66. Any suitable connector means, illustrated by reference numeral 65, which may be a belt, or chain, or gears, or the like, joins the line shaft 66 to the unwind unit 26. Similar connector means 67 join the line shaft 66 to the printer unit 36, and similar connector means 68 join the line shaft 66 to the folder unit 50. Thus, these units 26, 36, and 50 are operated by the line shaft 66, as illustrated in FIGURE 2.

A drive motor 70 is used to operate the punch unit 30. The drive motor 70 is connected to the punch unit 30 through a start-stop clutch 72 and suitable connector means 74. The start-stop clutch 72 is preferably similar to the start-stop clutch 64, discussed above.

A drive motor drives the perforation unit 44 through a speed control clutch 82, and a start-stop clutch 84, and suitable connector means 85. The motor 80 and the clutches 82 and 84 may be similar to the motor 60 and the clutches 62 and 64, respectively, discussed above.

It is to be understood that within the purview of this invention either of the speed control clutches 62 or 82 may be combined with its respective start-stop clutch 64 or 84. Also, within the purview of this invention various types of drive means, clutch means, and connector means may be employed.

Speed control It is to be understood that as the punch unit 30 alternately moves and stops the strip 14, the average rate of movement of the strip 14 through the punch unit 30 should be substantially equal to the rate of continuous movement of the strip 14 through the unwind unit 26. During operation of the strip handling apparatus of this invention as shown in FIGURES 1 and 2, all of the units are operated at a given normal rate but may be operated at rates other than normal.

As stated above, the strip 14 forms a loop 28 between the unwind unit 26 and the punch unit 30. A plurality of photocell members 90 and 92 are used to sense changes in the length of the loop 28 so that the length of the loop 28 is maintained between a predetermined minimum length and a predetermined maximum length. Of course, the length of the loop 28 is dependent upon the rate of operation of the unwind unit 26 with respect to the rate of operation of the punch unit 30. The photocells 90 and 92 are electrically connected to a speed control unit 94 which, in turn, is joined to the speed control clutch 62. The speed control unit 94 may comprise suitable electrical relays and/ or electronic valve means which are joined to a source of electrical energy (not shown) and which are also joined to the speed control clutch 62 and which control theamount of electrical current flowing to the speed controlclutch 62, which, preferably, as stated above, may be an eddy current clutch which transmits rotational energy in accordance with the amount of electric current flow therein.

The photocells 90 provide a signal to the speed control unit 94 if the loop 28 becomes less than a desired predetermined length. When the speed control unit 94 receives such a signal from the photocells 90, the speed control unit 94 causes the speed control clutch 62 to operate the line shaft 66 at a higher rate of speed. Thus, the unwind unit 26 is operated at a higher rate of speed. Thus, the unwind unit 26 operates at a higher rate with respect to the rate of operation of the punch unit 30 so that the relative rates of operation tend to lengthen the loop 28 between the unwind unit 26 and the punch unit 30.

If the length of the loop 28 between the unwind uni-t 26 and the punch unit 30 becomes greater than a given desired length, the photocells 92 sense the condition and provide a signal to the speed control unit 94. When this occurs, the speed control uni-t 94 causes the speed control clutch 62 to decrease the rate of operation of the line shaft 66. Therefore, the rate of operation of the unwind unit 26 with respect to the punch unit 30 changes to tend to shorten the loop 28 between the unwind unit 26 and the punch unit 30 Changes in the length of the loop 40 between the printer uni-t 36 and the perforation unit 44 are sensed by photocells 98 and 100. Of course, the length of the loop 40 is determined by the rate of operation of the printer unit 36 with respect to the perforation unit 44. When the length of the loop 40 is less than a desired predetermined value, this condition is sensed by the photocells 98, which provide a signal to the speed control unit 102. This signal causes the speed control clutch 82 to decrease the rate of operation of the perforation unit 44.

When the length of the loop 40 is greater than a given desired length, this condition is sensed by the photocells 100, which provide a signal to the speed control unit 102. The speed control unit 102 is, preferably, similar to the speed control unit 94, discussed above. This signal causes the speed control clutch 82 to increase the rate of operation of the perforation unit 44. Thus, the photocells 98 and 100 through the speed control unit 102 govern the rate of oepration of the perforation unit 44 with respect to the printer unit 36.

Thus, it is understood that all of the units 26, 30, 36, 44, and 50 operate together sequentially upon the continuous strip 14 to produce partially severed business forms carried in the strip 14 of business form material. Even though some of the units of the apparatus of this invention operate upon portions of the continuous strip 14 while portions of the strip 14 are at rest and some of the units of this apparatus operate upon portions of the strip 14 while those portions are in continuous motion, the units are so coordinated and controlled that they all operate together at a high rate of speed and perform successive operations upon the strip 14.

Stop control The verification portion 30b of the punch unit 30 has connected thereto a stop control unit 108. The stop control unit 103 is connected to the start-stop clutch 64, and to the start-stop clutch 72 and to the start-stop clutch 84. The stop control uni-t 108, preferably, comprises electrical relays and/or contactors and/or electronic valve means which normally maintain closed electric circuits between a source of electrical energy and the start-stop clutches 64, 72, and 84. However, upon proper signal from the verification portion 30b of the punch unit 30 the stop control unit 108 opens the electrical circuits to the start-stop clutches 64, 72, and 84. If, the verification portion 30b of the punch unit 30 finds that any of the punched holes 32 punched by the portion 30a is not entirely correct, the stop control unit 108 receives a stop signal from the verification portion 30b of the punch unit 30. When such a signal occurs, the stop control unit 108 causes the start-stop clutches 64, 72, and 84 to immediately stop the entire apparatus. Thus, the strip handling apparatus of this invention is operated only when the punching operation in the punch unit 30 is correct.

FIGURE 7 illustrates another example of a continuous strip or web 114 as it appears as it is removed from a roll, such as the roll 16. The strip 114 is provided with strip feed holes 118 which, are disposed at the edges of the strip 114 and some of the strip feed holes 118 are disposed at the central portion of the strip 114.

Business forms such as the forms 120 are printed on either side of the central holes 118. The strip or web 114 may be severed longitudinally at the center thereof during operation thereupon by the apparatus shown in FIGURES l and 2. Preferably, the web 114 is longitudinally severed at the center thereof in the folder unit 50. Prior to reaching the folder unit 50, the strip 114 is operated upon by the units 26, 30, 36, and 44, in the manner discussed above with respect to the strip 14.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

The invention having thus been described, the following is claimed:

1. Strip handling apparatus comprising:

:first operator means for operating intermittently upon a strip, first drive means to drive said first operator means at a substantially constant rate,

second operator means for operating intermittently upon the strip,

second drive means to drive the second operator means at a variable rate and including speed control means, third and forth operator means for operating continuously upon the strip, said third operator means preceding said first operator means, said forth operator means following said first operator means,

third drive means for continuously driving said third and fourth operator means at a variable rate and including speed control means,

means responsive to variations in the rate of the third drive means with respect to the rate of the first drive means for controlling the third drive means to maintain said variations within predetermined limits, means responsive to variations in the rate of the second drive means with respect to the rate of the third drive means for controlling the second drive means to maintain the variations Within predetermined limits.

2. The apparatus of claim 1 in which the first operator means comprises punching mechanism.

3. The apparatus of claim 1 in which the third operator means comprises unwind mechanism and the fourth operator means comprises printing mechanism.

4. The apparatus of claim 1 in which the second operator means comprises perforating mechanism.

5. Strip handling apparatus comprising:

punch means,

first drive means to drive the punch means at a substantially constant rate,

perforation means,

second drive means to drive the perforation means at a variable rate and including speed control means, unwind means and printing means and folding means, the unwind means preceding the punch means, the printing means following the punch means and preceding the perforation means, the folding means following the perforation ineans,

third drive means to continuously drive the unwind means and the printing means and the folding means at the same rate and including speed control means for adjusting said rate,

means responsive to variations in the rate of the third drive means with respect to the rate of the first drive means for controlling the third drive means to maintain said variations within predetermined limits, means responsive to variations in the rate of the second drive means with respect to the rate of the third drive means for controlling the second drive means to maintain the variations within predetermined limits.

6. Strip handling apparatus comprising:

first operator means for operating intermittently upon a strip, first drive means to drive s aid first operator means at a substantially constant rate, the first drive means including a start-stop clutch,

second operator means for operating intermittently upon the strip,

second drive means to drive the second operator means at a variable rate and including speed control means,

the second drive means also including a start-stop clutch,

third and fourth operator means for operating continuously upon the strip, said third operator means preceding said first operator means, said fourth operator means following said first operator means, third drive means for driving said third and fourth operator means at a variable rate and including speed control means, the third drive means also including a start-stop clutch,

means responsive to variations in the rate of the first drive means with respect to the rate of the third drive means for controlling the third drive means to maintain said variations within predetermined limits,

means responsive to variations in the rate of the second drive means with respect to the rate of the third drive means for controlling the second drive means to maintain the variations within predetermined limits,

means responsive to operation of the first operator means for simultaneously operating all of the start- :stop clutches for stopping all of the operator mean.

1'. Strip handling apparatus comprising:

first operator means for operating intermittently upon a strip,

first driv means to drive said first operator means at a substantially constant rate,

second operator means for operating intermittently upon the strip,

second drive means to drive the second operator means at a variable rate and including speed control means,

third and fourth operator means for operating continuously upon the strip, said third operator means preceding said first operator means, said fourth operator means following said first operator means,

third drive means for continuously driving said third and fourth operator means at a variable rate and including speed control means,

means responsive to variations in the rate of the third drive means with respect to the rate of the first drive means for controlling the third drive means to maintain said variations within predetermined limits,

means responsive to variations in the rate of the second driv means with respect to the rate of the third drive means for controlling the second drive means to maintain the variations within predetermined limits,

means responsive to the operation of the first operator means for stopping all of said drive means.

8. Strip handling apparatus comprising:

first operator means for operating intermittently upon a strip,

first drive means to drive said first operator means at a substantially constant rate,

second opera-tor means for operating intermittently upon the strip,

second drive means to drive the second operator means at a varibale rate and including speed control means,

third and fourth operator means for operating continuously upon the strip, said third operator means preceding said first operator means, said fourth operator means following said first operator means,

third drive means for continuously driving said third and fourth operator means at a variable rate and including speed control means,

first control means, the first control means being responsive to variations in the rate of the third drive means with respect to the rate of the first drive means for controlling the third drive means to maintain said variations within predetermined limits, the first control means including means for sensing the length of a loop in the strip between the first operator means and the second operator means,

second control means, the second control means being responsive to variations in the rate of the second drive means with respect to the rate of the the third drive means for controlling the second drive means to maintain the variations within predetermined limits, the second control means including means for sensing the length of a loop in the strip between the fourth operator means and the second operator means.

References Cited by the Examiner UNITED STATES PATENTS 674,356 5/1901 Feister 2702l 2,548,136 4/1951 Auer 101-226 X- 2,655,098 10/1953 Dutro et al. 10l227 X 2,687,090 8/1954 Car-roll 101227 3,069,155 12/1962 Fulk 270-18 EUGENE R, CAPOZJO, Primary Examiner. 

1. STRIP HANDLING APPARATUS COMPRISING: FIRST OPERATOR MEANS FOR OPERATING INTERMITTENTLY UPON A STRIP, FIRST DRIVE MEANS TO DRIVE SAID FIRST OPERATOR MEANS AT A SUBSTANTIALLY CONSTANT RATE, SECOND OPERATOR MEANS FOR OPERATING INTERMITTENTLY UPON THE STRIP, SECOND DRIVE MEANS TO DRIVE THE SECOND OPERATOR MEANS AT A VARIABLE RATE AND INCLUDING SPEED CONTROL MEANS, THIRD AND FORTH OPERATOR MEANS FOR OPERATING CONTINOUSLY UPON THE STRIP, SAID THIRD OPERATOR MEANS PRECEDING SAID FIRST OPERATOR MEANS, SAID FORTH OPERATOR MEANS FOLLOWING SAID FIRST OPERATOR MEANS, THIRD DRIVE MEANS FOR CONTINUOUSLY DRIVING SAID THIRD AND FOURTH OPERATOR MEANS AT A VARIABLE RATE AND INCLUDING SPEED CONTROL MEANS, MEANS RESPONSIVE TO VARIATIONS IN THE RATE OF THE THIRD DRIVE MEANS WITH RESPECT TO THE RATE OF THE FIRST DRIVE MEANS FOR CONTROLLING THE THIRD DRIVE MEANS TO MAINTAIN SAID VARIATIONS WITHIN PREDETERMINED LIMITS, MEANS RESPONSIVE TO VARIATIONS IN THE RATE OF THE SECONE DRIVE MEANS WITH RESPECT TO THE RATE OF THE THIRD DRIVE MEANS FOR CONTROLLING THE SECOND DRIVE MEANS TO MAINTAIN THE VARIATIONS WITHIN PREDETERMINED LIMITS. 